I evaluated you software and like it a lot. I have some intersting suggestions por the application:
The Purchase Order module could add a commercial proposal management feature. Or in other separate module, or either allow to manage "N" commercial propostal / quotations for the same purchase order (considering file attachment of of documents received)
The email sent to technician or either to requester could be more "well formated", I mean, it could be an HTML message or either a "copy" of the request preview / request visualization on application (by the way a nice interface, congratulations)